Supercritical Water Processing of Extra Heavy Crude in a Slurry-Phase Up-Flow Reactor System

ABSTRACT

A system and method for upgrading heavy crude oil. The system comprises: a system for blending a catalyst with the heavy crude to produce a crude/catalyst slurry, a source of supercritical water, a system for blending the supercritical water with the crude/catalyst slurry, infecting the feed slurry into the bottom of an tip-flow reactor, carrying out a reaction between the water and the crude to produce treated hydrocarbons, and separating the treated hydrocarbons into a heavy stream and a light stream. The first separator is in fluid communication with the tipper half of the reactor. A second separator receives the light stream and separates it into gases, liquid hydrocarbons, and water. A system and method of generating hydrogen for the process through in situ shift reaction, generating carbon monoxide either in situ through the injection of air inside the reactor or externally by gasification of unreacted resid or produced gases.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

FIELD OF THE INVENTION

The present invention relates generally to a reactor system and apparatus for treating extra heavy crude petroleum using supercritical water in a slurry-phase up-flow reactor system. More specifically, this invention provides a process for upgrading extra heavy hydrocarbon crudes into lighter hydrocarbon synthetic crudes having lower viscosities and high enough API gravities to allow the synthetic crude to be transported in a pipeline. In particular, the present invention is directed to a reactor that combines thermal and catalytic treatment of heavy petroleum crude in a slurry phase reactor, in which a feed comprising hydrocarbons, catalyst and supercritical water is fed into the bottom of the reactor and products are removed from the top.

BACKGROUND OF THE INVENTION

Current technologies for converting heavy crudes, bitumens, etc., to lighter products include: (1) hydrocracking or (2) combinations of coking or thermal operations followed by some form of hydroprocessing. In the former, reformation of heavy crude oil into lighter hydrocarbon products is accomplished by contacting the crude oil with hydrogen and catalyst which decomposes and cracks the hydrocarbons into lighter hydrocarbons. Various designs have been utilized in the past for hydrotreatment of heavy petroleum oil. For example, in some systems, a liquid petroleum feedstock is cracked in a down-flow fixed-bed reactor. The hydrocarbon products are removed from the bottom of the reactor.

This type of system is vulnerable to coking and may require frequent catalyst replacement. Other problems include flooding of the catalyst bed and plugging of the catalyst bed with metals present in the heavy oil. In addition, current crude conversion technologies are capital intensive and require a sophisticated refinery infrastructure including hydrogen plants, fuel, and feed for the production of hydrogen or a source of hydrogen.

Hence, there remains a need to provide a reactor system that avoids the problems associated with fixed bed catalyst reactors. There is also a need to provide a process that provides a cheaper source of hydrogen and apparatus for simultaneous and combined thermal and catalytic treatment of extra heavy crude oil.

SUMMARY OF THE INVENTION

The present invention provides a process and apparatus for simultaneous and combined thermal and catalytic treatment of extra heavy crude oil in a slurry phase reactor that avoids the problems inherent with fixed bed catalyst reactors. The present invention uses a slurry-phase up-flow reactor that provides more efficient use of catalyst and easier recovery of reaction products. By using a single reactor vessel and providing improved operating life, the present concept can produce products with essentially the sane products at lower investment and operating costs.

The present invention allows a cost-effective and efficient conversion of extra heavy hydrocarbon crudes, tar sands and bitumens. More specifically, this invention provides a process for converting hydrocarbons with a relatively cheaper source of hydrogen, in the presence of supercritical water and a suitable catalyst. Alternatively, hydrogen can also be produced in-situ through a shift reaction i.e., reaction of carbon monoxide with water, either through the production of CO by partial oxidation of hydrocarbons through the injection of air/oxygen into the system or by injection of CO produced externally in a gasifier by gasifying unconverted residue or product gas. In this process a heavy hydrocarbon crude having a high viscosity and low API is converted into a lighter synthetic hydrocarbon crude having a lower viscosity and an API gravity high enough to allow the synthetic crude to be transported through a pipeline. The upgraded liquid stream is sometimes referred to in the industry as “Synthetic Crude Oil” and can be pipelined to a refinery for further treatment, such as the production of transportation fuel.

Thus, the present invention comprises a combination of features and advantages that enable it to overcome various problems of prior system. The various characteristics described above, as well as other features, will be readily apparent to those skilled in the art upon reading the following detailed description of the preferred embodiments of the invention, and by referring to the accompanying drawings

BRIEF DESCRIPTION OF THE DRAWING

For a more detailed description of the preferred embodiment of the present invention, reference will now be made to the accompanying drawing, which is a schematic diagram of a system constructed in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the Figure, one embodiment of a system 10 constructed in accordance with the present invention includes a wellhead 12, storage tank 20, slurry mixer 30, reactor 40, hot separator 50, and three-phase separator 60. Wellhead 12 receives raw crude from a well and feeds it via line 14 into storage tank 20. In some situations, the raw crude may include an amount of water and may or may not be an emulsion. Wile the present system does not require removal of this water before the crude is processed, the water can be removed using any suitable technique if removal is desired.

In storage tank 20, the crude oil is mixed with a catalyst that enters tank 20 via line 22. Any suitable catalyst can be used, for example the catalyst may be any suitable combination of catalysts compromising a water gas shift catalyst and a hydrogenation catalyst, such as are known in the art, may be used. It is preferred that the catalyst be provided as a fine powder so that slurry conditions within the reactor call be maintained. It will be understood that mixing of the crude with the catalyst could be carried out in a separate tank from storage tank 20, if desired. The mixture of catalyst and crude oil leaves tank 20 via line 24, is pressurized by a pump 25 and heated in a preheater 26, and is injected into slurry mixer 30.

Supercritical water is also injected into mixer 30 via a feed line 32. Tank 30 is preferably operated at supercritical conditions of >3000 psi and >350° C. Before entering mixer 30, the supercritical water is raised to a desired pressure and temperature by a pump 35 and heater 34. Pump 35 may be any suitable pump and heater 34 may be a resistance heater, gas-fired boiler, or any other suitable heater types. In slurry mixer 30, the hot crude/catalyst mixture from line 24 is injected into the supercritical water. The resulting crude/catalyst/water slurry is immediately injected into a reaction zone at the bottom of reactor 40.

In reactor 40, heavy crude is thermally cracked at the reaction conditions and produces free radicals, which in turn extract hydrogen from the supercritical water to produce lighter hydrocarbons. Reactor 40 is preferably sized such that the reactants remain in reactor 40 for an average residence time of from about 5 to about 60 minutes, more preferably 10-20 min. If desired, part or all of the unconverted hydrocarbons from downstream in the process can be recycled into the reactor via line 58 and carbon monoxide and/or hydrogen from a downstream gasifier (described below) can also be injected into reactor 40 via line 59. If desired, additional hot (>300° C.) air may be introduced and injected into the reactor vessel through gas inlet 44. The purpose of this air is to produce hydrogen in situ via partial oxidation and shift reaction.

The heavy crude/catalyst/water slurry may be injected into reactor 40 via one or more nozzles in the reactor vessel. The preheating step and the supercritical water phase preferably provide sufficient heat to the incoming feed to ensure that thermal decomposition occurs. After the desired residence time in the reactor, lighter hydrocarbon products exit from the top of the reactor via line 42. Because reactor 40 is an up-flow reactor, line 42 is preferably in fluid communication with the upper half, and more preferably the upper quarter, of reactor 40. In some embodiments, (not shown) unconverted heavy residue along with solids (catalysts, metals and coke formed) may be withdrawn from the bottom of the reactor.

Reaction products, including gaseous and liquid hydrocarbons and supercritical water are removed from the top of reactor 40 via line 42 and enter hot separator 50. Hot separator 50 is preferably operated such that lighter products including the gaseous hydrocarbons and gaseous or supercritical water are removed from the top of separator 50 via line 52, while heavier products, including unconverted resid/pitch, which may contain metals, catalysts and/or coke, is removed from the bottom of hot separator 50 via line 54.

All or a portion of the unconverted resid/pitch heavy products from line 54 can be recycled directly to reactor 40 via line 58 in order to increase the yield of lighter products. Alternatively, if desired, some or all of the materials in line 54 can be passed through an optional vacuum flash unit 55 and separated into more volatile hydrocarbons and less volatile hydrocarbons. If desired, the more volatile hydrocarbons can be added to liquid hydrocarbon product in line 64 via line 67.

Alternatively, or in addition, a portion of the heavy products from line 54 can be subjected to gasification and/or catalytic oxidation, through line 56 in an optional gasifier 57 so as to produce syngas (CO+H₂). Gasifier 57 can be a plasma gasifier, or other suitable device. The resulting gas or syngas can be injected into reactor 40 via line 59 in order to increase hydrogenation therein.

If desired, additional hydrogen can be produced inside the reactor through shift reaction with the production of CO through partial oxidation by injecting air into the heavy crude/catalyst/water slurry via line 44 into reactor 40. If CO or syngas is added to reactor 40, it is preferred to use as the catalyst a compound comprising zirconium oxide (10-80%) and iron oxide. The iron oxide may be present as a catalyst support. Alternatively, the catalyst may be any suitable combination of catalysts compromising a water gas shift catalyst and a hydrogenation catalyst.

The products leaving the top of hot separator 50 via line 52 preferably enter three-phase separator 60, which further separates the stream into three fractions. In certain embodiments, the fractions may comprise a gaseous top product, which exits via line 62, a liquid hydrocarbon product, which exits via middle line 64, and a water phase, which exits via bottom line 66. The upgraded liquid product in line 64 is known as “synthetic crude oil” and can be pipelined to a refinery for further treatment to produce transportation fuel. If desired, the water in line 66 may be cleaned and recycled to the supercritical system via line 68. A cleaning unit (not shown) such as are known in the art may be included in line 68. If desired, the gaseous phase in line 62, which usually consists of C₁-C₄ hydrocarbons, CO₂ and H₂S, may be cleaned in an acid gas treatment plant 69, and recycled to the gasifier 57 through line 63, in order to generate additional syngas for the reactor 40.

The catalyst added to the crude preferably comprises a mixture of two or more inorganic metal compounds, such as zirconia and iron oxide. The catalyst is preferably provided as particles or as a fine powder (50-1000 mesh) and may comprise two or more metals selected from the group consisting of: ZrO₂, Fe₂O₃, K₂O₃, NaCO₃, other metal oxides such as Ni/Co, metal carbonates, and combinations thereof.

In operation, the slurry containing catalyst and heavy crude is heated to about 100 to 500° C. (200 to 930° F.) before being injected into the supercritical water. Likewise, the water is heated to supercritical conditions, preferably a temperature greater than 300° C., more preferably greater than 370° C. (700° F.), and a pressure greater than 22 MPa (3200 psi). Temperature and pressure within reactor 40 are preferably maintained between 400 and 500° C. (752 and 932° F.) and between about 20.7 and 34.5 MPa (3000 and 5000 psig). In hot separator 50 downstream of reactor 40, temperature and pressure are preferably maintained between 300 and 400° C. (572 and 752° F.) and between about 13.8 and 20.7 MPa (2000 and 3000 psig).

While preferred embodiments of this invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit or teaching of this invention. For example, while storage tank 20 and slurry mixer 30 are disclosed as two separate components, it will be understood that they could be combined into a single device. Likewise, feed lines and outflow lines could be repositioned or reconfigured in a manner other than that shown in the Figure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims which follow, the scope of which shall include all equivalents of the subject matter of the claims. 

1. A system for treating heavy crude oil, comprising: a system for blending a catalyst with the heavy crude to produce a crude/catalyst slurry; a source of supercritical water; a system for blending the supercritical water with the crude/catalyst slurry to produce a crude/catalyst/water slurry; an up-flow reactor for carrying out a reaction between the water and the crude to produce treated hydrocarbons; a reactor feed for injecting said crude/catalyst/water slurry into the bottom of the reactor; and a reactor outflow line in fluid communication with the upper half of the reactor, said reactor outflow line receiving substantially all of said treated hydrocarbons.
 2. The system according to claim 1, further including a first separator receiving treated hydrocarbons from said reactor outflow line, said first separator separating said treated hydrocarbons into a heavy stream and a light stream.
 3. The system according to claim 2, further including a second separator receiving said light stream and separating said light stream into a gaseous stream, a liquid hydrocarbon stream, and a water stream.
 4. The system according to claim 2, further including a gasifier receiving and gasifying at least a portion of said heavy stream to produce a gas, wherein said gas is recycled to said reactor.
 5. The system according to claim 4, further including a second separator receiving said light stream and separating said light stream into a gaseous stream, a liquid hydrocarbon stream, and a water stream, and further including a line for recycling at least a portion of the produced gaseous stream from second separator to said gasifier.
 6. The system according to claim 1, further including an injector for injecting air or oxygen into said reactor.
 7. The system according to claim 1 wherein at least a portion of said heavy stream is recycled to said reactor as a liquid.
 8. The system according to claim 1, further including means for recycling the water stream from the second separator to the supercritical water system.
 9. The system according to claim 8, further including means for cleaning the recycled water.
 10. The system according to claim 1 wherein the catalyst is selected from the group consisting of water gas shift catalysts, hydrogenation catalysts, and combinations thereof.
 11. The system according to claim 1 wherein the catalyst is provided as a fine powder less than 1000 mesh.
 12. The system according to claim 1 wherein the catalyst comprises at least one material selected from the group consisting of: ZrO₂, Fe₂O₃, K₂O₃, NaCO₃, NiO, Ni₂O₃, oxides of cobalt, other metal oxides, metal carbonates, and combinations thereof.
 13. The system according to claim 1 wherein the catalyst comprises zirconia.
 14. A system for treating heavy crude oil, comprising: a system for blending a catalyst with the heavy crude to produce a crude/catalyst slurry; a source of supercritical water; a system for blending the supercritical water with the crude/catalyst slurry to produce a crude/catalyst/water slurry; an up-flow reactor for carrying out a reaction between the water and the crude to produce treated hydrocarbons; a reactor feed for injecting said crude/catalyst/water slurry into the bottom of the reactor; a reactor outflow line in fluid communication with the upper half of the reactor, said reactor outflow line receiving substantially all of said treated hydrocarbons; a first separator receiving treated hydrocarbons from said reactor outflow line, said first separator separating said treated hydrocarbons into a heavy stream and a light stream; a second separator receiving said light stream and separating said light stream into a gaseous stream, a liquid hydrocarbon stream, and a water stream; a gasifier receiving and gasifying at least a portion of said heavy stream-n to produce a gas, wherein said gas is recycled to said reactor; and a line for recycling at least a portion of the produced gaseous stream from second separator to said gasifier; wherein at least a portion of said heavy stream is recycled to said reactor as a liquid.
 15. A method for treating heavy crude oil, comprising: a) blending a catalyst with the heavy crude to produce a crude/catalyst slurry; b) providing a source of supercritical water; c) blending the supercritical water with the crude/catalyst slurry to produce a crude/catalyst/water slurry; d) injecting said crude/catalyst/water slurry into the bottom of an up-flow reactor; e) reacting the water and the crude in the reactor to produce treated hydrocarbons; and f) removing the treated hydrocarbons from the upper half of the reactor.
 16. The method according to claim 15, further including the step of g) separating said treated hydrocarbons into a heavy stream and a light stream.
 17. The method according to claim 16, further including the step of h) separating said light stream into a gaseous stream, a liquid hydrocarbon stream, and a water stream.
 18. The method according to claim 16, further including gasifying at least a portion of said heavy stream to produce a gas and recycling the gas from the gasifier to the reactor.
 19. The method according to claim 15, further including injecting air or oxygen into said reactor so as to generate carbon monoxide in situ to produce additional hydrogen.
 20. The method according to claim 15, further including sending at least a portion of the produced gaseous stream to a gasifier to generate additional syngas.
 21. The method according to claim 15, further including recycling at least a portion of said heavy stream to said reactor as a liquid.
 22. The method according to claim 15, further including recycling at least a portion of the water stream to the supercritical water source.
 23. The method according to claim 22, further including cleaning the recycled water.
 24. The method according to claim 15 wherein the catalyst is selected from the group consisting of water gas shift catalysts, hydrogenation catalysts, and combination thereof.
 25. The method according to claim 15 wherein the catalyst is provided as a fine powder less than 1000 mesh.
 26. The method according to claim 15 wherein the catalyst comprises at least one material selected from the group consisting of: ZrO₂, Fe₂O₃, K₂O₃, NaCO₃, NiO, Ni₂O₃, oxides of cobalt, other metal oxides, metal carbonates, and combinations thereof.
 27. The method according to claim 15, further including producing hydrogen in the up-flow reactor.
 28. The method according to claim 27 wherein the hydrogen is produced by reacting carbon monoxide with water, and wherein the carbon monoxide is produced by partial oxidation of hydrocarbons or by gasifying unconverted residue or product gas. 